Automatic radio tuning mechanism



Feb. 27, 1934. HARTE 1,948,710

AUTOMATIC RADIO TUNING MECHANISM Filed April 1, 1929 [1V VENTOR PatentedFeb. 27, 1934 UNITED STATES PATENT OFFICE Frank Harte, New York, N. Y.,assignor to Reuben Papert, New York, N. Y.

Application April 1, 1929.

4Claims.

My invention relates to time controlled mechanism and more particularlyto an apparatus for automatically tuning a radio receiving set over apredetermined period of time. The apparatus,

l which may be either included in the construction of the receiver ormanufactured separately as an attachment thereto, is designed to bringabout the automatic tuning of the standard radio set to a particularbroadcasting station at any particular time or to a plurality ofstations in any predetermined order at periodic intervals.

The invention has for its object to provide an apparatus whereby, uponthe selection in advance of a program of any length of time, and 16 theproper setting of the switchboard comprising one element of my newapparatus, the desired stations will be automatically tuned in at theproper times. My invention further contemplates, and I have providedfor, the selection of either a continuous or a discontinuous programover a specific interval of time, the automatic tuning to the desiredstation or stations being accomplished only at such periods as have beenpreviously designated. A still further object of my invention is theelimination of the necessity of any adjustment whatsoever during theentire period of time for which the apparatus has been designed and forwhich the desired program has been selected. This period may be as highas twenty-four hours, although obviously, a shorter period, forinstance, twelve hours, should satisfy the most ardent "radio fan".Furthermore, my automatic tuning mechanism accomplishes not only theswitching necessary to bring the set into a condition of tuning for theparticular station desired at any definite hour or subdivision thereof,but also turns the radio set itself on and off for any predeterminableperiod of time. Other more specific objects will appear from thedescription hereinafter.

A particular embodiment of my invention is illustrated in theaccompanying drawing in which 1 is a switchboard determining the orderand frequency of switching and on which a particular one of severalstations may be tuned in at any predetermined time, held tuned for anydesired period, and then another station tuned in or the set completelyturned ofi. This switchboard is provided with a number of jacks 2arranged on the surface of the board in horizontal rows and verticalcolumns. The jacks are all of the double contact open circuit type, i.e., the two contacts 3 and 4 of each jack are normally in the openposition. The contact 3 of each jack is connected in multiple with thecorresponding Serial No. 351,537

contact 3 of each of the other jacks in the same vertical column, andthe second contact 4 of each jack is connected, also in multiple, withthe second contact 4 of each jack in the same horizontal row. Eachvertical column of multiple contacts is connected separately to variableresistance elements 5 which regulate the flow of current through relay6, operating at approximately 10 volts. The number of resistanceelements 5 thus corresponds to the number of vertical columns of jacks,these resistances being indicated in the drawing as R1 to R24 inclusive.The other ends of these resistance units are connected in multiple toone side of the main power line, preferably a 110 volt line, at point a.

The arrangement of jacks on the switchboard in the particular embodimentillustrated in the drawing is such that the horizontal rows of jackscorrespond to the stations and the vertical columns to the units of timeat which switching from one station to another, or from the off positionto an operable position, or vice versa, is to be accomplished. Thenumber of jacks on the switchboard is determined by the number ofstations the automatic tuning mechanism has been designed to include inits operative range, the frequency of switching, i. e., tuning from oneposition to another, and the length of the period for which the desiredprogram can be selected be forehand. In the apparatus herein shown anddescribed the switchboard and associated mechanism has been designed fora selection of four broadcasting stations to which the receiving set maybe automatically tuned. Switching is done once every half hour, over atwelve hour period. While a selection of four stations is no less thanthe demand to which the average receiving set is subjected in anyparticular locality, the switchboard illustrated is merely an example ofwhat under ordinary circumstances would be considered of ample selectivecapacity. It is obvious that the selective capacity, as well as thefrequency of switching and the length of time for which a program may bechosen in advance, for which the mechanismmay be designed and con- 100structed, is unlimited.

Since the ofi position, controlled by one of the horizontal rows ofjacks, is the equivalent, in point of operation and necessary equipment,to a station, a total of one hundred and twenty jacks 106 are requiredon the switchboard. Each of these jacks is designed to receive a metalplug 7 having an insulated cap which when inserted in a jack, serves toconnect the two contacts thereof. For

an apparatus designed for operation over a period 110 of twelve hoursduring which time switching, or change of stations, is done at intervalsof a half hour in the extreme, and a selection of four stations and anoff position, the number of plugs to be provided with each switchboardis twentyfour as will appear more clearly hereinafter.

For determining the specific times when the switching mechanism is to beactuated, and for starting th sequence of operations n at the periodicswitching, I employ a clock 8 of the usual construction and mechanismbut provided with a dial on which are distributed, at regular intervalsalong its periphery, contact points 9. Assuming that switching is to bedone every half hour, there would be twenty-four of these contact pointson the dial arranged at half hourly intervals. The hour hand 10 of theclock is rotated in the usual manner by the clock mechanism and makessuccessive contact with points 9. In order to obtain a more nearlyinstantaneous switching, two additional contact points 11 and 12 areprovided at the hour and half-hour marks as determined by the minutehand 13. With these points 11 and 12, the said minute hand only, makescontact. Since the angular velocity of the hour hand is small, anyslight variation on the part of the hour hand with respect to the shaftwould result in a large deviation in the time of switching from theselected time. Hence the minute hand, with an angular velocity twelvetimes as great as that of the hour hand, is employed, with a consequentreduction in any error in time of switching.

The connection between the switchboard and clock comprises lead wiresiifrom the twentyfour contacts traversed by the hour hand to thecorresponding vertical column of jacks on the switchboard. The points 11and 12, contacted by the minute hand, are connected in multiple, throughrelay 6, the function of which will be hereinafter more particularlydescribed, to the 110 volt line at point b. When the apparatus isconstructed without the points 11 and 12 on the clock dial (as it wellmay be) the electrical connection between the hands of the clock and therelay 6 may be made by means of the shaft of the clock upon which saidhands are mounted.

For the mechanical operation of tuning, i. e., bringing the tuningelement or elements into the position corresponding to the wave-lengthof the broadcasting station to the program of which it is desired tolisten, I employ a 110 volt motor 16, either A. C. or D. C., dependingon the source of supply. This motor is attached by any suitablemechanical coupling device such as gears, pulleys, etc., to the tuningshaft 1'7. A reducing train of gears 18, between said shaft and the worm19 of the motor, may be used to obtain the reduction of speed necessaryfor maintaining a slow rotation of the tuning shaft 17. This tuningshaft may be made to control any number of variable tuned circuits byany of the methods familiar to those skilled in the art. The radio set,therefore, while of necessity of the so-called one dial type", may haveany number of variable tuned circuits so long as they are controlled bythe turning of one shaft. Since all radio sets may be built with tuningcontrols continuously variable in one direction, any limitation of mynew apparatus to sets having tuning controls continuously variable inone direction, is not a practical limitation. Furthermore, the automaticcircuit can be so arranged, for instance, by proper gearing, as toreverse the direction of rotation of the tuning elements when saidelements have been turned to their extreme positions.

Attached to the tuning shaft, and rotating therewith, is a contact arm20 adapted to pass over and contact with, a number of switch points 21,22, 23, and 24 arranged in a circular groove 25 upon an insulated board26. Each switch point is adjustable in position and is connected to ahorizontal row of jacks on the switchboard, and corresponds, in itsposition, to the tuned position of the tuning elements for the stationdesignated by that row. Since all modern receiving apparatus is made sothat the tuning positions of the elements are confined within an arc of180, the switch points will be within that are. The remaining portion ofthe periphery of the disc or board 26 is occupied by a circular strip ofmetal 27 which corresponds to the off" position and is thereforeconnected to the row of multiple contacts on the switchboard designatingsuch off position. While in the preferred construction of my apparatusthe contact member 27 is a circular strip of metaioccupyin the entireportion of the disc not included in the tuning arc, it is obvious thatcontact 27 may be a point contact similar to contacts 21 to 24. Y

The positions of the switch points or contacts 21 to 24 or those of anynumber of such contacts, depending upon the number of stations which theapparatus is designed to include in its selective capacity, aredetermined as follows:

A particular row of jacks on the switchboard is selected to correspondto a particular station, for instance, station WEAF. In the embodimentillustrated station WEAF occupies the position on the board having thehighest wave length of the stations provided for. Station WEAF ismanually tuned in and the position of the tuning elements on theparticular set for the particular 10- cality thus determined. Theswitchpoint 21, which is nearest in position to the maximum wavelengthposition of the tuning elements, is then put in a position on disc 26such that arm 20 is in contact therewith. The positions of the otherswitchpoints 22, 23, 24, etc., along the periphery of the board aresimilarly determined. Since in standard radio practice the positions ofthe tuning element or elements of receiving apparatus of identicaldesign are identical or very nearly so, the positions of the switchpoints on the board can be determined at the factory where theparticular type of set is manufactured. It

is, of course, preferable for best results, to make.

the determination at the exact locality and under the particularconditions of use of the receiving set.

Two relays, 6 and 28, connected as shown in the drawing, complete theapparatus. The function of the former, heretofore referred to, is tostart and stop the motor. It is of the normally-open contact type. Relay28 is of the normally-closed type and is used to turn the radio set onand off. Both relays should, for best results, operate on les than 10volts, 10 milliamperes, so that the resistances R1 to R24 may be of ahigh value, for instance, 10,000 ohms. The resistance R15, in the linefrom the horizontal row of jacks on the switchboard corresponding to theoff position, to the set operating relay 28, is similar to and of thesame resistance value as the resistance elements R1 to R24.

For disconnecting the automatic mechanism hereinabove described, Iprovide a switch 29 in the main power line of the automatic apparatus.Thus, when no use is desired to be made of the automatic feature, when,for instance, no particular program has been mapped out but a constantattendance on the radio set is desirable, the tuning shaft can be turnedmanually after throwing the switch 29. The switch is the regulationswitch whereby the set is turned on and off.

The operation of the apparatus is as follows:

In the normal condition of the switchboard all of the plugs occupy of!positions. A desired program having been decided upon, to commence withthe tuning in of a particular station at a particular hour, forinstance, station WEAF at 12:00 o'clock, then with switches 29 and 30both on, the plug in the 12:00" vertical column is removed from the 06"row and placed in the horizontal "WEAF" row, but stillin the 12:00"column. If, at 12:30 station WJZ is to be tuned in, the plug in the12:30" column is removed from the off row and placed in the horizontalrow designating WJZ. Thus the entire previously mapped out program ofstations to be tuned in at intervals can be arranged for a period oftime governed only by the designed capacity of the apparatus. If it isdesired that any station remain tuned in for a longer period than theinterval for which the mechanism has been constructed (in theillustrated case, one-half hour), the operator need but place the plugsin the successive vertical columns controlling the desired period oftime into the successive jacks in the row designating the stationdesired to remain tuned in. To illustrate, continuing the examplaryprogram outlined above, if at one o'clock station WOR is to be tuned in,the plug in the 1:00 vertical volumn is placed in its jack in the WOR"horizontal row. If WOR. is to remain on till three o'clock, the severalplugs in the 1:30", 2:00, and 2:30 columns are also placedin the WORrow. If the set is to be turned 01f from three until four o'clock, theplugs in the 3:00 and 3:30 columns are left in the off row. This offposition may thus be considered the equivalent of a station positionwith the exception that the set is turned off during the interval inwhich a plug occupies the 011" position.

When the desired program has been arranged as outlined hereinabove, theautomatic mechanism will function as follows: At 12 o'clock, the circuitof relay 6 will be closed from point b on one of the power lines,through the relay, through the hands of the clock (both minute and hourhand being on 12" oclock) and the resistance R1, to a point a on thesecond of the power lines. Relay 6, being in circuit will thereforeoperate, placing the 110 volts of the line on the motor. The motorrotates, and with it, at a greatly reduced rate due to the reductiongear train 18, the tuning shaft 17 and contact arm 20. When the contactarm, in its revolution upon the board 26, comes in contact with switchpoint 21, corresponding to the position of the tuning elements for thereception of the program of station WEAF as theretofore determined andhereinabove described, a circuit from the point e on one side of relay 6to point b on the other side of said relay and connected to the arm 20,is completed, so that the relay 6 is short-circuited, releasing thevoltage from the motor which consequently stops. Station WEAF is nowtuned in. The circuit from the point 0 to the point 12 is traceable asfollows: from point 0, through the hands of the clock, up the verticalvolumn 12:00" on the switchboard to the horizontal row WEAF", to switchpoint 21, contact arm 20, to point b. The contact 21 should be broadenough to allow a sufficient interval of time for the relay to releaseand the motor to stop without the contact arm 20 being carried past thepoint 21. When the relay has been short-circuited, and the power takenoff the motor, the latter will stop quickly without the use of anybraking mechanism due to the amount of frictiondeveloped by the rotatingshaft and reducing gears.

At 12:30, the circuit for relay 6 would be completed through the hourhand on the 12:30 contact and the minute hand onthe 6 (12) contact, ofthe clock and through R2. Relay 6 would operate again and turn on themotor. At this time, however, contact point 23, corresponding to theposition of the tuning elements for the reception of station WJZ, wouldbe connected to the point 0 and relay 6 would be short-circuited and themotor stopped when the contact arm reached switch point 23, leaving WJZtuned in. A similar sequence of operating steps would take place at 1:00for the tuning in of station WOR. At 1 :30. however, since WOR is toremain tuned in, contact arm 20 would still be on the contact point 22,corresponding to the position of the tuning elements for the receptionof WOR, there 'would be no operation of the relay 6, it being alreadyshortcircuited, and consequently there would be no operation of themotor. At 3 o'clock, the circuit for relay 6 would be made through theclock, and R5 and the motor would again be set in oper ation, the plugbeing in the off3:00 position. This time, however, point 0 would beconnected to the metal contact strip 27 and the motor would 110 turnuntil arm 20 made contact with the contact strip 2'1 when it would stop,due to the shortcircuiting of relay 6. At 3:30, since a plug is in the o-3:30" position, no change would be effected. At 4 oclock, the switchingwould be 115 resumed as indicated.

The circuit for relay 28 is also completed through contact strip 27 andthe contact arm 20, so that when these two elements are in contact,

i. e., in any off position, relay 28 is operated, 120 breaking the linesupplying power to the radio set. No power is thus consumed by the setwhen the automatic mechanism is in the "off" position, the set being aseffectively turned oil as if no automatic apparatus were attachedthereto. Of 125 course, a small amount of power is necessary to keep therelay 28 operative.

Although I have described a specific embodiment of my invention, it isto be understood that the'invention is not restricted to such particularembodiment. Various modifications thereof in detail and in thearrangement of the parts may be made by those skilled in the art withoutdeparting from the invention.

I claim:

1. In combination with a radio receiving set, an apparatus of the kinddescribed comprising a clock, a switchboard, a series of double contactopen-type jacks thereon, a plurality of resistance elements, a motor, anelectric circuit including power lines supplying power to said motor, atuning shaft in said receiving set, two relays, the clock having on itsdial face a plurality of contact points each connected by suitablewiring to the series of jacks arranged in columns and rows on saidswitchboard, a plurality of plugs for completing the circuit throughsaid jacks, electric wiring connecting each of said contact points withone of the contacts of one of the series of jacks connected in multipleand through 150 one of said resistance elements to one of the main linessupplying power to the motor actuating the tuning shaft of the receivingapparatus, a contact arm connected to said tuning shaft and rotatingtherewith, a board rigidly mounted about said shaft and having thereon aplurality of contact points with which said contact arm A is adapted tocontact, and electric wiring connecting said contact points to thesecond set of jack contacts connected in multiple.

2. The apparatus claimed in claim 1 having two additional contact pointslocated at predetermined positions on the dial oi the clock andconnected through a relay to the second of the power lines.

3. The apparatus claimed in claim 1 having an additional contact on therigidly mounted board corresponding to the oii position and inelectrical connection with the second series of Jack contacts on theswitchboard corresponding to said oil position and, through a secondrelay, with the first of the power lines 4. In combination with a radioreceiving set, an apparatus of the kind described, comprising a clock, aswitchboard having a series of double contact open-type jacks thereon, aplurality 'of resistance elements, a motor, an electric circuitincluding power lines supplying power to said motor, a tuning shaft insaid receiving set,

tworelaymtheclockhavingonitsdialiacea plurality 0! contact points eachconnected by suitable wiring to the series 01! lacks arranged in columnsand rows on said switchboard. a plurality oi. plugs completing thecircuit through said jacks, electric wiring connecting each of saidcontact points with one of the contacts 0! one of the series of jacksconnected in multiple and through one 01' said resistance elements toone of the main lines supplying power to the motor actuating the tuningshaft of the receiving apparatus, a contact arm connected to said tuningshaft and rotating'therewith, a board rigidly mounted about said shaftand having thereon a plurality of contact points with which said contactarm is adapted to contact, electric wiring connecting said contactpoints to the second set of jack contacts connected in multiple, twoadditional contact points located at predetermined positions on the dialof the clock and connected through one of said relays to the second ofsaid main lines, and an additional contact on said rigidly mounted boardcorresponding to the "of!" position and in electrical connection withsaid second series of jack contacts on the switch- 1

